On the S65 V8 M3 models, the stock exhaust headers flow very well while the catalysts present the largest obstacle and power loss. the Macht Schnell Bypass Track Pipes were designed specifically for race/track use, and offer a cost-effective means of removing the 400 cell restrictive primary catalytic converters on all 2008-2013 M3s. Bypass Track Pipes allow you to make two single cuts to your stock midpipe section, removing the catalytic converters, and clamping the largest diameter straight pipe in their place using the provided high-end/premium exhaust clamps. This eliminates the largest source of exhaust restriction, unleashing considerable power gains (~20hp) and a very obvious improvement in acceleration.

Macht Schnell Bypass Track Pipes permit you to retain your OEM secondary cats and resonators, keeping noise levels tame enough for even the most stringent sound limitations found at many track events (nearly stock decibel levels), and also keeping costs to a minimum. No welding is required for installation, simply cut and bolt into place using supplied exhaust clamps.

The primary cats are being deleted, but you are still retaining the scondary 200 cell cats. The stock 200 cell cats are twice the cell count of an Akrapovic X-pipe. If you have ever smelt an Akrapovic it would be less than that.